Three-dimensional structure of a pre-catalytic human spliceosomal complex B - PubMed (original) (raw)

doi: 10.1038/nsmb761. Epub 2004 Apr 18.

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Three-dimensional structure of a pre-catalytic human spliceosomal complex B

Daniel Boehringer et al. Nat Struct Mol Biol. 2004 May.

Abstract

Major structural changes occur in the spliceosome during its transition from the fully assembled complex B to the catalytically activated spliceosome. To understand the rearrangement, it is necessary to know the detailed three-dimensional structures of these complexes. Here, we have immunoaffinity-purified human spliceosomes (designated B Delta U1) at a stage after U4/U6.U5 tri-snRNP integration but before activation, and have determined the three-dimensional structure of B Delta U1 by single-particle electron cryomicroscopy at a resolution of approximately 40 A. The overall size of the complex is about 370 x 270 x 170 A. The three-dimensional structure features a roughly triangular body linked to a head domain in variable orientations. The body is very similar in size and shape to the isolated U4/U6.U5 tri-snRNP. This provides initial insight into the structural organization of complex B.

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